Tutorial Layout CSS di HTML

CSS singkatan dari Cascading Style Sheets. CSS digunakan untuk menampilkan HTML dengan baik. 
Sepeti layout seperti ini:

 Caranya adalah dengan menggunakan sebuah folder css di dalam directory HTML.

Kode CSS harus disimpan dalam strukture CSS, dan bisa juga disimpan disebuah file.
Contoh CSS Coding:
.ddsmoothmenu{
    float: left;
}

.ddsmoothmenu ul{
    z-index:100;
    margin: 0;
    padding: 0;
    list-style-type: none;
}

/*Top level list items*/
.ddsmoothmenu ul li{
    position: relative;
    display: inline;
    float: left;
}

/*Top level menu link items style*/
.ddsmoothmenu ul li a {
    display: block;
    padding: 0 30px;
    height: 40px;
    line-height: 40px;
    font-size: 12px;
    color: #2f2f2f;  
    text-decoration: none;
    outline: none;
    text-align: center;
}

* html .ddsmoothmenu ul li a{ /*IE6 hack to get sub menu links to behave correctly*/
display: inline-block;
}

.ddsmoothmenu ul li a.selected, .ddsmoothmenu ul li a:hover { /*CSS class that's dynamically added to the currently active menu items' LI A element*/
    color: #fff;
    background: #2f2f2f;
}

/*1st sub level menu*/
.ddsmoothmenu ul li ul {
    position: absolute;
    left: 0;
    padding: 10px 0 0;
    display: none; /*collapse all sub menus to begin with*/
    visibility: hidden;
    background: #313131;
    border-bottom: 4px solid #000
}

/*Sub level menu list items (undo style from Top level List Items)*/
.ddsmoothmenu ul li ul li{
display: list-item;
float: none;
}

/*All subsequent sub menu levels vertical offset after 1st level sub menu */
.ddsmoothmenu ul li ul li ul{
top: 0;
}

/* Sub level menu links style */
.ddsmoothmenu ul li ul li a{
    font-weight: 400;
    width: 130px; /*width of sub menus*/
    height: 30px;
    padding: 0 30px;
    line-height: 30px;
    font-size: 11px;  
    text-align: left;
    background: none;
    color: #ccc;
    border-bottom: 1px solid #222;
    border-top: 1px solid #444;
}

.ddsmoothmenu ul li ul li a.selected, .ddsmoothmenu ul li ul li a:hover {
    color: #fff;
    font-weight: 700;
    background: #222;
}

/* Holly Hack for IE \*/
* html .ddsmoothmenu{height: 1%;} /*Holly Hack for IE7 and below*/


/* ######### CSS classes applied to down and right arrow images  ######### */

.downarrowclass{
position: absolute;
top: 12px;
right: 7px;
}

.rightarrowclass{
position: absolute;
top: 6px;
right: 5px;
}

/* ######### CSS for shadow added to sub menus  ######### */

.ddshadow{
position: absolute;
left: 0;
top: 0;
width: 0;
height: 0;
}

.toplevelshadow{ /*shadow opacity. Doesn't work in IE*/
opacity: 0.5;
}

/* menu */